The science of perimetry relates to testing the field of vision of the eye. When such tests are performed regularly, certain diseases and/or disease courses can be detected and/or observed.
Known perimeters have an observational surface, which is designed in the manner of a hemispherical shell, for example, and forms a concave projection surface in the interior. The patient to be examined looks into the concave hemisphere, with the eye that is to be tested being situated at the center of the hemisphere. As soon as the eye to be tested is positioned at the center of the hemisphere, the patient is instructed to keep his eyes on a fixation mark at the center of the projection area of the hemisphere. Once this has been done properly, the sensitivity of the eye to stimuli in the field of vision is tested and recorded. This is done by presenting light stimuli at various locations on the observational surface, while the patient reports in each case, e.g., by depressing a switch, whether or not the corresponding light stimulus has been observed. As a result, the sensitivity of the eye to light stimuli at various locations in the field of vision can be determined and mapped.
Two fundamentally different perimetric test methods are known from the state of the art. In the first variant, so-called static perimetry, non-moving light stimuli are presented to the patient. By varying the luminous density of these light stimuli, the stimulus threshold at a certain location in the field of vision can be ascertained, for example. In addition to static perimetry, there is also the known kinetic perimetry, in which the patient is presented with moving light stimuli, with a point of light being guided along a predetermined line of movement over the observational surface, for example. The limits of peripheral vision can be determined by kinetic perimetry in particular.
Both static and kinetic field of vision examinations can be performed using known perimeters because the moving and/or non-moving presentation of light stimuli requires completely different perimeter designs. However, recent studies have shown that describing a patient's field of vision by static perimetry on the one hand and/or by kinetic perimetry on the other hand remains incomplete in either case. Both examination methods have advantages and disadvantages and neither, when taken alone, can completely describe the condition of the field of vision.